Method and device for supplying several working gases, and its application to an installation for assembling electronic components

ABSTRACT

A method for delivering at least two working gases from a common air supply comprising the steps of depleting the air in O 2  in order to obtain a first gas mixture having an O 2  content less than or equal to t 1 ; delivering at least a portion of this first gas mixture as a first working gas; depleting another portion of this first gas mixture in O 2  in order to obtain the second gas mixture having an O 2  content less than or equal to t 2 , wherein t 1  is greater than t 2 ; and delivering the second gas mixture as a second working gas.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method for delivering at least twoworking gases, having different limiting O₂ contents, from a common airsupply.

Many industrial processes require the use of N₂/O₂ working atmosphereshaving different limiting O₂ contents. Such processes are sometimesemployed on the same industrial site.

This is the case, for example, in the electronics industry in which thereflow-soldering and wave-soldering processes for assembling electroniccomponents make use of N₂/O₂ atmospheres typically having limiting O₂contents of respectively a few % in one case and a few thousand ppm inthe second case.

Depending on the limiting O₂ content to be obtained, several means fordepleting the air from the supply in O₂ may be used: cryogenicdistillation, adsorption of oxygen on a catalytic bed, combination ofoxygen with another gas, or selected permeation through a membrane.

In general, in order to deliver N₂/O₂ working atmospheres of differentlimiting O₂ contents for the implementation of industrial processes onthe same site, either separate delivery means are used, thus multiplyingthe working-gas delivery devices, or a single atmosphere feed is usedfor all the processes, thus resulting in superfluous depletion in O₂ forsome of the processes. Such solutions are not optimal.

The object of the invention is to remedy the abovementioned problem and,in particular, to provide an economic method for delivering workinggases having different limiting O₂ contents from a common air supply.

For this purpose, the subject of the invention is a method fordelivering at least two working gases from a common air supply, thelimiting O₂ contents, respectively t1 and t2, of which gases are suchthat t1 is greater than t2, characterized in that:

the air is depleted in O₂ in order to obtain a first gas mixture havingan O₂ content less than or equal to t1;

a portion of this first gas mixture is used to deliver the first workinggas;

another portion of this first gas mixture is depleted in O₂ in order toobtain a second gas mixture having an O₂ content less than or equal tot2; and

this second gas mixture is used to deliver the second working gas.

Depending on the particular embodiments, the method may include one ormore of the following characteristics:

said first and second gas mixtures are the working gases directly;

at least one oxygen-containing product resulting from one of saiddepletions in O₂ is recovered for the purpose of using thisoxygen-containing product;

the oxygen-containing product is superoxygenated air coming from thefirst depletion in O₂;

t₁ is greater than or equal to 0.5% (and preferably between 0.5% and10%) and t₂ is less than or equal to 1% (and preferably between 100 ppmand 5000 ppm).

The subject of the invention is also a device for delivering at leasttwo working gases, having different limiting O₂ contents, from a commonair supply, characterized in that it comprises:

first means of depletion in O₂;

second means of depletion in O₂;

means connecting an inlet of the first means of depletion in O₂ to theair supply;

means connecting an inlet of the second means of depletion in O₂ to anoutlet of the first means of depletion;

means for producing the first working gas, these being connected to anoutlet of the first means of depletion; and

means for producing the second working gas, these being connected to anoutlet of the second means of depletion.

Depending on particular embodiments, the device may include one or moreof the following characteristics:

the means for producing the working gases are means for tapping off thegas mixtures directly to the outlet of the means of depletion;

means of depletion in O₂ have an outlet for oxygen-containing product,and the device comprises means connecting this outlet to a unit forconsuming this oxygen-containing product;

the oxygen-containing product is superoxygenated air coming from thefirst means of depletion;

the first and/or second means of depletion in O₂ are means of depletionin O₂ by combination of the O₂ with another gas or by adsorption of theO₂ on a catalytic bed or else by selective permeation through amembrane.

Finally, the subject of the invention is a plant for the assembly ofelectronic components, comprising a chamber for storing electroniccomponents in a controlled atmosphere, the limiting O₂ content of theatmosphere in this chamber being t₁, and at least one machine forassembling the components in a controlled atmosphere, the limiting O₂content of the atmosphere in this machine being t₂<t₁, the plant beingcharacterized in that it comprises a device for delivering workinggases, which feeds said chamber with said first gas mixture and saidassembly machine with said second gas mixture.

The invention will be better understood on reading the description whichfollows, given solely by way of example, and with reference to theappended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows diagrammatically a device for delivering working gasesaccording to the invention, which feeds two user stations (9, 11) whoserequirements in working gas differ;

FIG. 2 shows schematically another device for delivering working gasesaccording to the invention, which feeds three user stations (7, 9, 11)whose requirements in working gas differ.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The device in FIG. 1 comprises first means 1 of depletion in O₂ byselective permeation through a polymer membrane and second means 3 ofdepletion in O₂ by catalytic combination of the latter with hydrogen.

This device is intended to deliver the working atmospheres for areflow-soldering oven 9 and for a wave-soldering machine, forming partof a plant for the assembly of electronic components.

Before their assembly in the reflow oven 9 or in the wave-solderingmachine 11, the electronic components are stored in theelectronic-component storage chamber 7 located upstream of the means 1.

The chosen working atmospheres at the various points in the plant shownare as follows:

air from the air supply 13 is tapped off in order to feed the storagechamber 7, this air having beforehand been filtered, removed of any dustand dried, using the apparatus 15;

the means 1 of depletion in O₂ use the conventional process of depletingthe air coming from the source 13 in O₂ by selective permeation througha polymer membrane, and delivering, at their residual outlet 2, an N₂/O₂mixture having in this case an O₂ content close to 1%. This mixturefeeds, on the one hand, an electronic-component reflow-soldering oven 9directly and, on the other hand, an inlet 4 of the second means 3 ofdepletion in O₂;

the second means 3 of depletion in O₂ use a conventional process forcatalytically combining oxygen with hydrogen in order to form water.These means 3 comprise a dryer making it possible to condense the waterproduced, and removed at 6, and to obtain a gas depleted in O₂ at theiroutlet 10.

The N₂/O₂ mixture produced at the outlet 10 of the means 3 has an O₂content close to 50 ppm, feeding an electronic-component wave-solderingmachine 11 directly.

The permeate mixture obtained at the second outlet 14 of the first means1 of depletion in O₂ is superoxygenated air having an O₂ content closeto 25%, used for feeding a superoxygenated-air-consuming unit 17.

This unit 17 may, for example, be an oven and may be located on the sameindustrial site as the plant for assembling the electronic components.The superoxygenated air obtained may thus be used to feed the flames ofburners intended to melt the glass involved in the manufacture oftelevision tubes.

The device according to the invention therefore makes it possible, bysuccessive depletions of the air from the source 13 in O₂, to feed withworking gases processes whose limiting O₂ contents are very different.

The method for delivering working gases employed is particularlyeconomical since, on the one hand, it uses common means of depletion ofO₂ to deliver working gases of different limiting O₂ content and, on theother hand, it eliminates the superfluous depletions of O₂.

More briefly, FIG. 2 illustrates a case in which first (1A), second (1B)and third (5) means of depletion in oxygen are used, these being,respectively:

a membrane separator 1A, making it possible to produce, at its residualoutlet 2, an N₂/O₂ gas mixture having a residual oxygen content close to10%, so as to feed a component-storage chamber 7 with this mixture;

a membrane separator 1B, making it possible to produce, at its residualoutlet 10, an N₂/O₂ gas mixture having a residual oxygen contenttypically ranging from 1 to 3%, so as to feed a componentreflow-soldering oven 9 with this mixture;

means 5 of deoxygenation by the catalytic reaction of oxygen withhydrogen in order to form water. These means 5 comprise a dryer makingit possible to condense the water produced, and removed at 8, and toobtain at their outlet 12 an N₂/O₂ mixture whose O₂ content is close to50 ppm, feeding an electronic-component wave-soldering machine 11directly.

What is claimed is:
 1. A method for delivering at least two workinggases from a common air supply, in an electronic component plantcomprising the steps of: depleting the air in O₂ in order to obtain afirst gas mixture having an O₂ content less than or equal to t1;delivering at least a portion of this first gas mixture as a firstworking gas to a chamber for storing electronic components in acontrolled first atmosphere; depleting another portion of this first gasmixture in O₂ in order to obtain a second gas mixture having an O₂content less than or equal to t2, wherein t1 is greater than t2; anddelivering the second gas mixture as a second working gas to at leastone machine for assembling the components in a controlled secondatmosphere.
 2. The method according to claim 1, comprising employingsaid first and second gas mixtures themselves as the working gases. 3.The method according to claim 1, further comprising recovering at leastone oxygen-enriched product resulting from one of said steps ofdepleting O₂ for further use.
 4. The method according to claim 3,wherein said oxygen-enriched product is superoxygenated air coming fromthe first step of depleting O₂.
 5. The method according to claim 1,wherein t1 is greater than or equal to 0.5%.
 6. The method according toclaim 5, wherein t1 is between 0.5% and 10%, and t2 is between 100 ppmand 5000 ppm.
 7. The method according to claim 5, wherein t1 is between0.5% and 10%.
 8. The method according to claim 1, wherein t2 is lessthan or equal to 1%.
 9. The method according to claim 8, wherein t2 isbetween 100 ppm and 5000 ppm.
 10. A method for delivering at least twoworking gases from a common air supply, the method comprising the stepsof: depleting the air in O₂ using a first O₂ depletion process in orderto obtain a first gas mixture having an O₂ content less than or equal tot1; delivering at least a portion of this first gas mixture as a firstworking gas; depleting another portion of this first gas mixture in O₂using a second O₂ depletion process in order to obtain a second gasmixture having an O₂ content less than or equal to t2, wherein t1 isgreater than t2; and delivering the second gas mixture as a secondworking gas; wherein said first O₂ depletion process and said second O₂depletion process cannot both be a process wherein O₂ is depleted byselectively permeating O₂ through a membrane.
 11. The method of claim10, wherein said first and said second O₂ depletion processes areselected from the group consisting of a process wherein O₂ is depletedby combining O₂ with another gas, a process wherein O₂ is depleted byabsorbing O₂ on a catalytic bed, and a process wherein O₂ is depleted bybeing selectively permeated through a membrane.
 12. A device fordelivering at least first and second working gases, comprising differentlimiting O₂ contents, from a common air supply, comprising: at leastfirst and second means for depleting the air in O₂; wherein said atleast first and second means for depleting the air in O₂ do not bothconstitute a means wherein O₂ is depleted by being selectively permeatedthrough a membrane; means connecting an inlet of the first means ofdepleting in O₂ to the air supply; means connecting an inlet of thesecond means of depleting in O₂ to an outlet of the first means ofdepletion; means for producing the first working gas connected to anoutlet of the first means of depleting; and means for producing thesecond working gas connected to an outlet of the second means ofdepletion.
 13. The device according to claim 12, wherein the means forproducing the working gases are means for tapping off the gas mixturesdirectly to the outlet of the means of depletion.
 14. The deviceaccording to claim 12, wherein the means of depleting in O₂ have anoutlet for an oxygen-enriched product, and the device further comprisesmeans connecting this outlet to a unit for consuming thisoxygen-enriched product.
 15. Device according to claim 14, wherein theoxygen-enriched product is superoxygenated air coming from the firstmeans of depleting.
 16. Device according to claim 12, wherein the firstand/or second means of depleting in O₂ are means of depleting in O₂ bycombination of the O₂ with another gas or by absorption of the O₂ on acatalytic bed or by selective permeation through a membrane.
 17. Thedevice according to claim 12, wherein said first and said second meansfor depleting the air in O₂ are selected from the group consisting of ameans wherein O₂ is depleted by combining O₂ with another gas, a meanswherein O₂ is depleted by absorbing O₂ on a catalytic bed, and a meanswherein O₂ is depleted by being selectively permeated through amembrane.
 18. A plant for the assembly of electronic components,comprising: a chamber for storing electronic components in a controlledfirst atmosphere, wherein said atmosphere has a limiting O₂ content inthis chamber of t1, and at least one machine for assembling thecomponents in a controlled second atmosphere, wherein said secondatmosphere has a limiting O₂ content of t₂<t₁, and a device fordelivering working gases, which feeds said chamber with a first gasmixture, as a first working gas, and said assembly machine with a secondgas mixture, as a second working gas; wherein said device for deliveringworking gases comprises: at least first and second means for depletingthe air in O₂; means connecting an inlet of the first means of depletingin O₂ to the air supply; means connecting an inlet of the second meansof depleting in O₂ to an outlet of the first means of depletion; meansfor producing the first working gas connected to an outlet of the firstmeans of depleting; and means for producing the second working gasconnected to an outlet of the second means of depletion.
 19. A devicefor delivering at least first and second working gases, comprisingdifferent limiting O₂ contents, from a common air supply, comprising: afirst O₂ depleting device; a second O₂ depleting device; wherein saidfirst and second O₂ depleting devices do not both operate using aprocess wherein O₂ is depleted by selectively permeating O₂ through amembrane; a supply of air in fluid communication with an inlet of saidfirst O₂ depleting device; a conduit connecting an inlet of the secondO₂ depleting device to an outlet of the first O₂ depleting device; asecond outlet to the first O₂ depleting device in fluid communicationwith a conduit which delivers said first working gas to a first desiredapplication; and an outlet to said second O₂ depleting device in fluidcommunication with a conduit which delivers said second working gas to asecond desired application.
 20. The device according to claim 19,wherein said first and/or second O₂ depleting device comprises amembrane separation device, a catalytic adsorption device, or a reactorfor reacting O₂ with another gas.
 21. The device according to claim 19,wherein said first application is a chamber for storing electroniccomponents in a controlled atmosphere.
 22. The device according to claim19, wherein said second application is a machine for assemblingelectronic components in a controlled atmosphere.
 23. A plant for theassembly of electronic components, the plant comprising: a chamber forstoring electronic components in a controlled first atmosphere, whereinsaid atmosphere has a limiting O₂ content in this chamber of t1; atleast one machine for assembling the components in a controlled secondatmosphere, wherein said second atmosphere has a limiting O₂ content oft2<t1; a device for delivering working gases which feeds said chamberwith a first gas mixture, as a first working gas, and said assemblymachine with a second gas mixture, as a second working gas; wherein saiddevice for delivering working gases comprises: at least first and secondmeans for depleting the air in O₂; wherein said at least first andsecond means for depleting the air in O₂ do not both constitute a meanswherein O₂ is depleted by being selectively permeated through amembrane; means connecting an inlet of the first means of depleting inO₂ to the air supply; means connecting an inlet of the second means ofdepleting in O₂ to an outlet of the first means of depletion; means forproducing the first working gas connected to an outlet of the firstmeans of depleting; and means for producing the second working gasconnected to an outlet of the second means of depletion.
 24. The plantaccording to claim 23, wherein said first and said second means fordepleting the air in O₂ are selected from the group consisting of ameans wherein O₂ is depleted by combining O₂ with another gas, a meanswherein O₂ is depleted by absorbing O₂ on a catalytic bed, and a meanswherein O₂ is depleted by being selectively permeated through amembrane.